[InstCombine] Add contributor guide #79007
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| * `m_OneUse(M)`: Check that the value only has one use, and also matches M. | ||
| For example `m_OneUse(m_Add(...))`. See the next section for more | ||
| information. | ||
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TODO: m_ElementwiseBitCast. It may confuse contributors when folding bitcast-related patterns.
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This one seems pretty exotic to me, compared to the other ones.
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@AtariDreams @elhewaty @ParkHanbum @SahilPatidar |
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we added this:
but I sill find the look through |
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what about adding when to use |
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One more thing that might be nice is an example or so of successful PRs new contributors can look at to get a sense of how all these rules play out. Either way though, I think at this point the document is clearly useful and would be happy with it going up in its current form. We can always add more later. |
Done. |
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Any more feedback on this? |
| Make tests minimal. Only test exactly the pattern being transformed. If your | ||
| original motivating case is a larger pattern that your fold enables to | ||
| optimize in some non-trivial way, you may add it as well -- however, the bulk | ||
| of the test coverage should be minimal. |
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TODO: Drop unused poison-generating flags/UB-implying attributes.
| One-use checks can be performed using the `m_OneUse()` matcher, or the | ||
| `V->hasOneUse()` method. | ||
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| ### Generalization |
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TODO: Be aware of poison-generating flags/FMF propagation.
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I'll go ahead and merge this so we can iterate further in-tree. |
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thanks for work to this!! I was very lost when I first contributed to LLVM and this will help me a lot. Q. when I can see this document from web site llvm.org? |
Document expectations for contributions to InstCombine, especially regarding test coverage and alive2 proofs.
Document expectations for contributions to InstCombine, especially regarding test coverage and alive2 proofs.